Airbag module

Abstract: An extruded motor vehicle airbag restraint module housing (22) including a cover (18) which is integral with one or both sides (14, 16) of the housing (22) and forms one or two release doors which may be defined by tear lines of reduced thickness. The housing (22) may be incorporated into a module in which an airbag (38) is attached inside the housing (22) by means of rods (40, 44) sewn into the bag (38) around a substantially rectangular mouth being received in semi-cylindrical channels (34, 36) on opposed sides of the housing. The cover (18) may be integral with one side (14) and adherable or weldable to an upper edge of the other side (16).

Description: This invention relates to vehicle airbag modules. More particularly, it relates to a passenger side airbag module comprising an extruded canister and novel airbag retention means. Conventional passenger side airbag modules comprise a reaction canister of steel or aluminum. The canister is trough-shaped and has an open top. A collapsed airbag is retained and supported within and near the top of the canister by a retainer or diffuser. The ends of the canister are closed by end plates. The end plates include openings for receiving and supporting a cylindrical gas generating inflator below the folded airbag. The canister includes means for retaining thereon a separate cover which may form a portion of the vehicle's instrument panel. Examples of prior art modules may be found in U.S. Patent 4,941,678 of Lauritzen el al. (on which the pre-characterising part of claim 1 is based) and the patents and applications referenced therein. In the airbag module including the Lauritzen canister the cover is formed separately from the canister sidewalls and engages them by ribs which snap into longitudinal channels in the sidewalls. It would be desirable to reduce both the weight and complexity of the passenger side airbag module assembly. It would also be desirable to provide such an assembly wherein the reaction canister has a closed top to both retain the airbag within the module and prevent foreign objects from entering the module prior to its installation in a vehicle. The primary object of the present invention is to provide a passenger side airbag module assembly which has an integral cover for protecting the folded airbag prior to installation. A preferred object is to provide such a reaction canister having improved means for assembling and retaining the folded airbag within the canister. Another object is to provide such an assembly which is lightweight and has substantially fewer parts than prior art modules. Other objects, features and advantages will become apparent from the following description and appended claims. DISCLOSURE OF INVENTION The foregoing objects are achieved by providing a reaction canister with a body and integral cover extruded from a high strength thermoplastic. The extrusion includes a pair of semi-cylindrical channels on the inner sidewalls of the canister for securing, by means of rods or dowels, the open mouth of the airbag. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an airbag module in accordance with the invention, partially broken away to illustrate its construction; FIG. 2 is an enlarged detail of a portion of the module of FIG. 1 ; FIG. 3 is a partial end view of a modified form of the invention of FIG. 1 ; FIG. 4 is a view similar to FIG. 3 illustrating a further modification of the invention; FIG. 5 is an end view of a portion of the reaction canister with the end plate removed, illustrating the airbag installation; and FIG. 6 is an enlarged detail of a portion of the mouth of the airbag of FIG. 5 . BEST MODE FOR CARRYING OUT THE INVENTION In accordance with the present invention, the reaction canister for a passenger side airbag module is extruded as a one-piece trough and cover. FIG. 1 illustrates such a canister 10 . The canister 10 includes a semi-cylindrical bottom portion 12 surmounted by left 14 and right 16 sidewalls. The left and right sidewalls define a top which is closed by an integral cover 18 . The canister 10 is a high strength thermoplastic which may be either unfilled or filled with reinforcement fibers such as glass, carbon, quartz, graphite, etc. Examples of suitable thermoplastics include, but are not limited to, nylon, polyvinylchloride, acrylonitrile-butadiene-styrene resin, and polyphenylene oxide based resins such as Noryl (a trademark of General Electric company). The extrusion may include any desired structural elements such as, for example, stiffening ribs 20 and end plate attachment channels 22 . End plates 24 and 26 are attached to the ends of the canister 10 by means of self-tapping screws 28 which are threaded into the ends of the attachment channels 22 . As will be apparent from FIG. 1 , the canister extrusion is in the form of a tube having a flat surface formed by the cover 18 . However, as shown in FIG. 2 , the cover 18 is formed with a tearline 30 in the form of a region of reduced thickness adjacent the sidewall 16 . The expanding airbag within the canister 10 causes the cover 18 to split along the tearline 30 , forming a door which opens along a hinge line 32 adjacent the left sidewall 14 , as illustrated in FIG. 1 . FIG. 3 illustrates a modified canister 10' wherein the tearline 30' is located in the center of cover 18 so as to form two doors 18a, 18b . A still further modification is illustrated in FIG. 4 . In this modification, the canister 10'' is extruded, not as a tube but as a trough having an open cover 18'' . In this version, after extrusion the cover 18'' is rotated downwardly into the closed position and secured by means of solvent-welding, cementing, or other methods, to close the top of the canister 10'' . As is illustrated in FIG. 5 , the inner surfaces of the left sidewall 14 and the right sidewall 16 carry parallel left semi-cylindrical channel 34 and right semi-cylindrical channel 36 . A folded airbag 38 is housed within the canister and above the channels. The airbag 38 has a rectangular mouth. The material forming opposite edges of the mouth is wrapped around a dowel or rod 40 which is retained by sewing or otherwise sealing the airbag material along the lines 42 as shown in FIG. 6. The completed airbag thus includes a rectangular mouth incorporating stiff rods 40 , 44 on opposite sides of the mouth. Assembly of the airbag module begins by cutting the extruded canister 10 to the desired length. The airbag is then folded and the two dowels 40 , 44 sewn into opposite sides of its rectangular mouth are inserted into the semi-cylindrical channels 34 , 36 as illustrated in FIG. 5 . The bag material extends through the slots running along the tops of the channels as illustrated. The end plates 24 , 26 are attached to the ends of the canister 10 by using the screws 28 . Thereafter a cylindrical gas generating inflator 46 is conventionally inserted through the end plate openings with its circular base 48 flush against the end plate 24 as illustrated in FIG. 1. Referring now to FIG. 5 , it will be apparent that opposite edges of the rectangular mouth of the airbag 38 are held apart by means of the rods 40 , 44 in the channels 34 , 36 . The other edges of the mouth are adjacent the respective end plates 24 , 26 . When a crash occurs, the gases generated by the inflator 46 rapidly fill the airbag 38 and the unrestrained edges of its mouth are simply urged against their respective endplates. The expanding bag splits the cover along its tearline 30 causing it to open as illustrated in either of FIGS. 1 and 3 . The cover 18 may, but need not be, a portion of the vehicle instrument panel. In any event, it both secures and retains the airbag within the module and serves as a protective covering to prevent foreign objects from entering the airbag and module cavity. It will now be apparent that the present invention substantially reduces the number of component parts required in an airbag module. It also simplifies the assembly of such a module, provides a protective cover, and results in a lighter weight module than has been known to the prior art.

Claims: A motor vehicle airbag restraint module housing comprising a trough-shaped housing (22) having a bottom portion connected to first and second sidewalls (14, 16) defining a top therebetween and first and second open ends and a cover (18) extending between said first and second ends for closing said top, characterised in that said cover (18) is integral with said housing. The housing of claim 1 wherein said cover (18) is integral with both of said first and second sidewalls (14, 16) to form a tube. The housing (22) of claim 1 wherein said cover (18) is integral with one sidewall (14, 16) and confrontable with the other sidewall (14, 16) so as to be weldable or adherable thereto. The housing of claim 1, 2 or 3 wherein said cover (18) defines a tearline (30) along its length between said first and second ends. The housing of any preceding claim wherein inner surfaces of said first and second sidewalls (14, 16) carry respective first and second substantially parallel, semi-cylindrical, channels (34, 36) extending between said first and second ends. An airbag assembly for use in a motor vehicle comprising a rigid trough-shaped housing (22) and cover (18) combination as claimed in any preceding claim, first and second end plates (24, 26) closing the respective first and second ends of said housing (22), an airbag (38) within said housing (22) having an open mouth, and an inflator (46) within said housing (22) connected to inflate the airbag (38) through its open mouth. The airbag assembly of claim 6 wherein said first and second channels (34, 36) extend along the length of the housing on respectively opposite sides of said inflator (46) and wherein said mouth of said airbag (38) is substantially rectangular and is secured to said channels (34, 36) by first and second rods (40, 44) carried by opposite sides of said rectangular mouth and retained within said first and second channels (34, 36) respectively. The airbag assembly of Claim 7 wherein said rods (40, 44) are sewn into said mouth of said airbag (38). A method of manufacturing an airbag restraint module assembly as claimed in Claim 6, 7 or 8 which comprises: (a) extruding a trough-shaped housing (22) and integral cover (18); (b) cutting said housing (22) and cover (18) to a desired length to form first and second open ends; (c) inserting into said housing a collapsed airbag (38) having an open, substantially rectangular, mouth; (d) inserting into said housing and between said open ends, a substantially cylindrical inflator (46), and (e) closing the first and second open ends with respective first and second end plates (24, 26). A method of manufacturing an airbag restraint module assembly as claimed in claim 9 wherein: (i) step a involves extruding a trough-shaped housing (22) with sides (14, 16) having inner surfaces defining first and second parallel semi-cylindrical channels (34, 36); and (ii) in step c the airbag (38) has first and second rods (40, 44) carried by opposite sides of said mouth and said airbag insertion involves inserting said collapsed airbag (38) into said housing (22) by sliding said first and second rods (40, 44) into the respective first and second channels (34, 36).

Inventors: GARNER BRETT R, MOSSI DEAN G, GARNER, BRETT R., MOSSI, DEAN G.
Applicants: AUTOLIV ASP INC, AUTOLIV ASP, INC.
Application year: 1994
Main classification: B60R21
IPC codes: B60R21